Steel ladles are used in the manufacture of steel. It is known to use different types of refractory materials in various areas of the ladles to achieve the most cost-effective lining. In this respect, different wear mechanisms exist in various areas within a steel ladle. Refractory materials that are appropriate for various areas have been developed.
For example, magnesia-carbon bricks are often used in slaglines of steel ladles. The term “slagline” refers to that area of the ladle sidewall that comes in contact with the slag layer that floats on top of the molten steel. On the other hand, either burned alumina bricks or alumina-magnesia-carbon bricks are often used in the “barrel” portion. The term “barrel” typically refers to the area of the ladle sidewall that is below the slagline. This is the area that is in contact with the molten steel when the ladle is filled to capacity. Magnesia-carbon bricks exhibit significantly better slag resistance than burned alumina bricks or alumina-magnesia-carbon bricks. Accordingly, magnesia-carbon bricks are well-suited for use in the slagline. Burned alumina bricks and alumina-magnesia-carbon bricks exhibit substantially poorer slag resistance than magnesia-carbon bricks, but have been heretofore considered the more cost-effective refractory selections for ladle barrels.
Alumina-magnesia-carbon bricks generally exhibit better erosion resistance, and are less subject to attack at the brick joints compared to burned alumina bricks. Brick “joints” refer to the areas where refractory bricks come into contact with each other after they are placed in the ladle lining. Thus, alumina-magnesia-carbon bricks are often used to line the barrel portions of steel ladles.
The decision of whether to use alumina-magnesia-carbon brick in steel ladle barrels is dictated by many factors. For instance, one factor to be considered in the selection of materials is the availability of raw materials. In this respect, about 65% to 90% of alumina-magnesia-carbon brick may be formed of bauxite. Calcined bauxite is made by taking an ore of aluminum composed largely of hydrous aluminum oxides, and heat-treating it to remove the hydrous phases and to increase the bulk specific gravity of the material.
Bauxite is basically a raw material bought and sold in a world market. In today's global economy, companies must compete worldwide for raw materials, such as bauxite. At the present time, a large proportion of refractory-grade bauxite comes from Asian countries, most notably, China. As with any commodity, demand and availability dictate the cost of bauxite. In addition, currency exchange rates and shipping costs can significantly affect the cost of bauxite to a refractory manufacturer.
Therefore, there is a desire to reduce cost fluctuation and provide refractory linings that are even more cost-effective and less susceptible to market fluctuation than those currently in use. Thus, fluctuations in global demand, shipping costs and currency rates can significantly affect the availability and cost of the raw materials needed to form refractory materials used to line steel ladles.
The present invention provides an improved refractory material for forming refractory linings for steel ladles, which refractory materials are more cost effective than refractory materials known heretofore.